What is the vagus nerve?

It's the talk of social media and health and wellbeing circles, but most of us have probably never heard of it. The vagus nerve. What is the vagus nerve, and what does it do? In broad terms, it's the communication line between the brain and a whole bunch of other organs, structures and processes. Theresa Larkin is Associate professor of Medical Sciences at the University of Wollongong, Australia.